Fluid catalytic cracking process and apparatus for maximizing light olefin yield and other applications

Abstract

Apparatus and processes herein provide for converting hydrocarbon feeds to light olefins and other hydrocarbons. The processes and apparatus include, in some embodiments, feeding a hydrocarbon, a first catalyst and a second catalyst to a reactor, wherein the first catalyst has a smaller average particle size and is less dense than the second catalyst. A first portion of the second catalyst may be recovered as a bottoms product from the reactor, and a cracked hydrocarbon effluent, a second portion of the second catalyst, and the first catalyst may be recovered as an overhead product from the reactor. The second portion of the second catalyst may be separated from the overhead product, providing a first stream comprising the first catalyst and the hydrocarbon effluent and a second stream comprising the separated second catalyst, allowing return of the separated second catalyst in the second stream to the reactor.

What is claimed: 
     
       1. A system for the conversion of hydrocarbons, comprising:
 a catalyst regenerator; 
 a first catalyst feed line for withdrawing a mixture comprising a first catalyst and a second catalyst from the catalyst regenerator, wherein the first catalyst has a smaller average particle size and/or is less dense than the second catalyst; 
 a riser reactor including a catalyst inlet for receiving the mixture from the first catalyst feed line, one or more hydrocarbon inlets, and an outlet for recovering an effluent comprising converted hydrocarbons and the mixture; 
 a second catalyst feed line for withdrawing an admixture comprising the first catalyst and the second catalyst from the catalyst regenerator; 
 a fluidization medium feed line for fluidizing the admixture withdrawn via the second catalyst feed line with a fluidization medium to form a fluidized admixture; 
 a catalyst separation system comprising an inlet for receiving the fluidized admixture from the second catalyst feed line, a first outlet, and a second outlet, the catalyst separation system configured to separate the fluidized admixture to form a first fraction comprising the first catalyst and the fluidization medium, recovered in the first outlet, and a second fraction comprising the second catalyst, recovered in the second outlet; 
 a third catalyst feed line for conveying at least one of the first fraction and the second fraction from the first outlet to the catalyst regenerator; 
 a fourth catalyst feed line for conveying the other of the at least one of the first fraction and the second fraction; 
 a reactor including one or more hydrocarbon inlets, a catalyst inlet, and an outlet, the catalyst inlet receiving catalyst from the fourth catalyst feed line, the reactor configured for contacting a hydrocarbon feedstock and the catalyst received from the fourth catalyst feed line and reacting at least a portion of the hydrocarbon to produce a converted hydrocarbon effluent, recovered via the outlet. 
 
     
     
       2. The system of  claim 1 , wherein the third catalyst feed line is configured to convey the first fraction to the catalyst regenerator, and wherein the fourth catalyst feed line is configured to convey the second fraction to the reactor catalyst inlet. 
     
     
       3. The system of  claim 1 , wherein the third catalyst feed line is configured to convey the second fraction to the catalyst regenerator, and wherein the fourth catalyst feed line is configured to convey the first fraction to the reactor catalyst inlet. 
     
     
       4. The system of  claim 1 , further comprising”
 a disengagement vessel configured:
 to receive the effluent from the reactor outlet and the effluent from the riser reactor; 
 to separate catalysts contained in the effluent from the reactor outlet and the effluent from the riser reactor from the converted hydrocarbon products; and 
 to recover the separated catalysts via a disengagement vessel catalyst outlet; and 
 
 a fifth catalyst feed line for conveying the recovered separated catalyst from the disengagement vessel catalyst outlet to the catalyst regenerator. 
 
     
     
       5. A system for the conversion of hydrocarbons, comprising:
 a catalyst regenerator; 
 a first catalyst feed line for withdrawing a mixture comprising a first catalyst and a second catalyst from the catalyst regenerator, wherein the first catalyst has a smaller average particle size and/or is less dense than the second catalyst; 
 a catalyst concentrator comprising an inlet for receiving the mixture from the first catalyst feed line, a light catalyst outlet and a dense catalyst outlet; 
 a fluidization medium feed line for fluidizing the mixture within the catalyst concentrator with a fluidization medium to form a fluidized admixture; 
 a catalyst separation system comprising an inlet for receiving the fluidized admixture from the light catalyst outlet, a first outlet, and a second outlet, the catalyst separation system configured to separate the fluidized admixture to form a first fraction comprising the first catalyst and the fluidization medium, recovered in the first outlet, and a second fraction comprising the second catalyst, recovered in the second outlet; 
 a second catalyst feed line for conveying at least one of the first fraction and the second fraction from the first outlet to the catalyst regenerator; 
 a third catalyst feed line for conveying the other of the at least one of the first fraction and the second fraction; 
 a reactor including one or more hydrocarbon inlets and a catalyst inlet receiving catalyst from the third catalyst feed line, the reactor configured for contacting a hydrocarbon feedstock and the catalyst received from the third catalyst feed line and reacting at least a portion of the hydrocarbon to produce a converted hydrocarbon. 
 
     
     
       6. The system of  claim 5 , wherein the second catalyst feed line is configured to convey the first fraction to the catalyst regenerator, and wherein the third catalyst feed line is configured to convey the second fraction to the reactor catalyst inlet. 
     
     
       7. The system of  claim 5 , wherein the second catalyst feed line is configured to convey the second fraction to the catalyst regenerator, and wherein the third catalyst feed line is configured to convey the first fraction to the reactor catalyst inlet.